A 20 y/o M arrives to your ED following an assault with a baseball bat. He had a transient LOC but is currently AAOx3. He has a multiple facial lacerations with significant left periorbital edema and ecchymosis. The patient is unable to open his left eye. When forcibly opened, you note significant proptosis. The patient states he cannot make out objects, only light. CT scan showed fractures of the left orbital floor and left lamina papyracea with a retrobulbar hemotoma.

Which of the following is an indication to perform an emergent lateral canthotomy in this patient? (scroll down for the answer)

a) IOP of 30

b) Sluggish pupil

c) Teardrop pupil

d) Ophthalmoplegia

e) Loss of vision

The correct answer is e) loss of vision

Orbital compartment syndrome is an ocular emergency. With limited ability to expand, orbital pressure can increase rapidly after a blunt traumatic injury and without intervention, irreversible vision loss can occur in as little as 90-120 minutes. Release of the lateral canthal tendon reduces intraorbital pressure allowing for the return of blood flow.

A lateral canthotomy is not indicated until the intraocular pressure greater than 40.

Ophthalmoplegia and an afferent pupillary defect are certainly suggestive of impending orbital compartment syndrome but are not an indication to initiate the procedure. Consider close monitoring and contact with your ophthalmologist. 

A teardrop-shaped pupil is a sign of globe rupture and is a contra-indication for a lateral canthotomy.

For a great review of the topic, check out the EP Monthly article Under Pressure: http://epmonthly.com/article/under-pressure/

Pryor, P. Under Pressure. Emergency Physicians Monthly. March 2012.

Popat H, et al. Blindness following retrobulbar hemorrhage – it can be prevented. Br J Oral Maxillofac Surg. 2007 Mar. 45(2):163-164.